62 FI distributer timing

[Ed Jennings]

I need some guideance from one of you engine experts: I have installed a newly rebuilt FI unit on my 62. The car is an original FI car, that had been missing the unit for quite a while. THe engine is a replacement 327, that is built somewhere close to the original 360 HP specs. Has about 10.5 compression, and a fairly stout cam, 2.02 heads, etc. I didn't build the engine, so I really don't know what the cam spec is. The previous owner described it as "radical but streetable". Whatever that means. This unknown cam may be a lot of my problem, but I want to explore all avenues before I change it.

The only way I can make the engine idle is with a lot of ititial advance. This was true with the carb that originally came with the car as well. It had an aftermarket tach drive distrubuter on it when I bought it. The ST12 calls for about 6 deg advance at 850 RPM. The only way I can get the engine to idle at all is with about 16 deg of advance. I really don't know what this number is, since it's off the timing scale! As a matter of fact, more is better,(faster, more stable) but I'm reluctant to give it any more advance. I had the same situation with the carb, but not as pronounced. Also, I'm getting a distinct engine vibration kicking in at about 2000 RPM. I had this with the carb also, but not until I fooled with the timing. I suspect it is timing related. (detonation???) The vibration is definately engine related and not chassis. I have considered the possibility that the timing marks on the balancer or on the engine are not correct. I didn't build the engine, so......? It was supposedly professionally built, but????. I'd really don't want to tear the engine down the find out, if I can avoid it. How much initial advance can I safely run? How about total? The ST 12 has some very low numbers for total as well. If I advance the timing much more than I have it now, I start getting some pinging if I lug the engine at all. I haven't tried any WOT operation yet. I want to get this timing issue settled before I get too froggy. Any advice would be greatly appreciated.

[Michael Ward (29001)]

Re: 62 FI distributer timing

I once had a similar situation on a carbureted engine. Ended up timing it by ear /trial and error (backed it off by two degress once it started pinging on hard acceleration). Turned out that the balancer outer ring had slipped, exactly as you mentioned.

Why not first off verify that your timing marks are correct, put #1 piston at TDC (a feeler through the plug hole is sufficient) and see where your timing marks line up.

Mike

[Duke Williams (22045)]

Re: 62 FI distributer timing

Our SBs typically produce the best torque curve with about 38 degrees total advance, and you want to get it in as quickly as possible, the limiting issue being detonation.

Measure you balancer and put a mark at 30 degrees. Then check the total timing with this mark. The best place to start is with it at 8 degrees on the index (38 total). If if runs without detonation, your're home free. The next step is to optimize the centrifugal advance by bringing it in quicker. Keep trying lighter springs until you get detonation, then go back to the last set.

I'm assuming you still have the original type dual point with no vacuum advance. On my '63 340 I run 14 initial with 24 centrifugal all in by 2350 RPM plus 16 degrees of vacuum advance all in by 8" so it's fully deployed at idle. Thus, I have a total of about 30 degrees at idle. Big cams idle better with lots of advance, but you have to be sure all the vacuum advance is in by whatever the idle vacuum is, which is probably low.

On my Cosworth Vega (106 degree lobe separation angle) I run 32 total - 15 initial, 17 centrifugal all in by 1800 plus 10 degrees vacuum all in by 10 inches. It idles at 1200 and pulls about 12 inches.

Duke

[Bill Clupper]

Re: 62 FI distributer timing

I think you may have several problems here, but in addition to those discussed, I'd be concerned about leakage of the cranking signal valve at idle if the cam is too radical. The factory '097 was about all the cam that a cranking signal valve could live with, a 30-30 is too much generally. You can fix this problem by using an electric solenoid (notmally closed) in the vacuun line and tying it into the cranking circuit. In addition, I'd have a competent shop get the distributer curve back to the original spec. A Fuelie should carry base timing of 10 degrees crank,(allowed 8 to 12) with centrifugal advance starting before 1000 rpm (crank speed) and about 11 degrees at 1600, 18 degrees at 3200, and full advance at 4500 (24 degrees) this plus the 10 degrees initial would give you 34 total. As duke says, you can go up to 38, but you need to start from a known base, especially with today's gas.

[Ed Jennings]

Re: 62 FI distributer timing

Thanks to all. Running fine now, I just didn't have the timing advanced sufficiently. At 900 RPM, I actually only had about 6 deg, at 12 it does fine. I had been getting my initial reading at too high an RPM.

[Dale Pearman]

Re: 62 FI distributor timing

You need to time that engine like the factory did. Rev it to 3000 RPM and set it at 36-38 degrees. Forget about initial timing. Let it fall wherever.

Dale.